1. Field of the Invention
The present invention relates to a process for producing indoline derivatives having the formula ##STR3## wherein R.sub.1 represents hydrogen atom, a lower alkyl, a lower alkoxyl, nitro or hydroxyl group; R.sub.2 represents hydrogen atom, a lower alkoxyl or nitro group; R.sub.3 represents hydrogen atom or a lower alkyl group and at least one of R.sub.1, R.sub.2 and R.sub.3 is a lower alkyl, a lower alkoxyl or nitro group; and X represents a halogen atom, which are used as intermediates of indoles which are starting materials for producing agricultural chemicals, medicines, dyes and other industrial products.
2. Description of the Prior Arts
It has been known to produce indoline derivatives by a cyclization of 2-aminophenethyl alcohols having ##STR4## wherein R.sub.1, R.sub.2 and R.sub.3 are defined above in the presence of hydrochloric acid as follows. ##STR5##
However, in the method, 2-amino phenethyl alcohols (II) are easily decomposed by heating and by-products of polymers are formed in the reaction whereby, it has been difficult to obtain indoline having high purity in high yield.